From 7459f27dd4bb9b60067ac49ee2c6be93d20c2c1e Mon Sep 17 00:00:00 2001
From: Lars Wendler <polynomial-c@gentoo.org>
Date: Thu, 13 Feb 2020 13:16:16 +0100
Subject: [PATCH] Prefer pkgconfig in FindLAPACK

---
 Modules/FindLAPACK.cmake | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Modules/FindLAPACK.cmake b/Modules/FindLAPACK.cmake
index c9629769f0..de852d562c 100644
--- a/Modules/FindLAPACK.cmake
+++ b/Modules/FindLAPACK.cmake
@@ -7,6 +7,10 @@ FindLAPACK
 
 Find Linear Algebra PACKage (LAPACK) library
 
+Version modified for Gentoo Linux.
+If a valid PkgConfig configuration is found, this overrides and cancels
+all further checks.
+
 This module finds an installed Fortran library that implements the
 LAPACK linear-algebra interface (see http://www.netlib.org/lapack/).
 
@@ -186,6 +190,22 @@ macro(CHECK_LAPACK_LIBRARIES LIBRARIES _prefix _name _flags _list _threadlibs _a
   #message("DEBUG: ${LIBRARIES} = ${${LIBRARIES}}")
 endmacro()
 
+# first, try PkgConfig
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(PC_LAPACK lapack)
+if(PC_LAPACK_FOUND)
+  foreach(PC_LIB ${PC_LAPACK_LIBRARIES})
+    find_library(${PC_LIB}_LIBRARY NAMES ${PC_LIB} HINTS ${PC_LAPACK_LIBRARY_DIRS} )
+    if (NOT ${PC_LIB}_LIBRARY)
+      message(FATAL_ERROR "Something is wrong in your pkg-config file - lib ${PC_LIB} not found in ${PC_LAPACK_LIBRARY_DIRS}")
+    endif (NOT ${PC_LIB}_LIBRARY)
+    list(APPEND LAPACK_LIBRARIES ${${PC_LIB}_LIBRARY})
+  endforeach(PC_LIB)
+  find_package_handle_standard_args(LAPACK DEFAULT_MSG LAPACK_LIBRARIES)
+  mark_as_advanced(LAPACK_LIBRARIES)
+else(PC_LAPACK_FOUND)
+message(STATUS "No PkgConfig configuration for LAPACK found; starting more extensive search.")
+
 set(LAPACK_LINKER_FLAGS)
 set(LAPACK_LIBRARIES)
 set(LAPACK95_LIBRARIES)
@@ -494,3 +514,5 @@ endif()
 
 cmake_pop_check_state()
 set(CMAKE_FIND_LIBRARY_SUFFIXES ${_lapack_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES})
+
+endif(PC_LAPACK_FOUND)
-- 
2.25.0